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Abstract

The invention relates to an enzymatic process for the stereoselective preparation of a hetero-bicyclic alcohol enantiomer, characterized in that a substantially pure enantiomer of the general formula ##STR1## wherein X is O, S, NH, N--(C.sub.1 -C.sub.4)alkyl or CH.sub.2 ; Y.sub.1, Y.sub.2 and Y.sub.3 are each independently hydrogen or substituents selected from halogen, C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy, C.sub.1 -C.sub.4 haloalkyl, nitro and cyano; the NO.sub.2 substituent is attached to the bicyclic ring system in the 5-or 7-position; and the C*-atom has either the R or the S configuration; is prepared from its corresponding alcohol racemate by the following successive reaction steps: (1) stereoselective esterification, (2) separation of the alcohol from the ester produced, (3) hydrolysis of the ester to produce the corresponding alcohol enantiomer, and (4) conversion of the alcohol enantiomer into the starting racemate under basic conditions in order to allow its reuse. The invention also relates to a substantially pure alcohol enantiomer of formula I, to the use of the enantiomer for the preparation of a pharmacologically active piperazine derivative, and to substantially pure enantiomeric intermediates.

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First Claim